In the spring of 1940, Britain was virtually without allies. Germany was already well on the way to occupying a
large part of Europe and Sir Henry Tizard realized that it would not be long before Britain's productive capacity could not match that of Germany and the
countries then in her possession. He recognized that if America did not enter the war, Britain simply could not win without the research and productive capacity
of the North American continent. This was particularly true in the field of electronics which was already playing a crucial part in the conduct of the war.

He therefore made the bold suggestion that Britain should hand over her war-time secrets to the USA in exchange
for research and productive capacity. This did not get a good response from his colleagues in the first instance, but when France fell, the wisdom of his
proposal was apparent. Winston Churchill became personally involved and talked directly to Roosevelt about the possibility of a Mission being sent to the USA
for this purpose. So fast did things move in those days that agreement to dispatch such a Mission was reached between Britain and America in July, members of
the Mission were chosen in August and they arrived in Washington at the beginning of September 1940. The membership of the Mission was:

Sir Henry Tizard (Mission Leader)

Brigadier F.C.Wallace (Army)

Captain H.W.Faulkner (Navy)

Group Captain F.L.Pearce (RAF)

Professor John Cockcroft (Army Research)

Dr, E. G . Bowen (Radar)

A.E.Woodward Nutt (Secretary)

The Service representatives were all senior people with recent operational experience. Brigadier Wallace was an M
C from World War I; he was in charge of the antiaircraft defenses at Dunkirk and was one of the last men to leave the beaches. Captain Faulkner had served in
the Atlantic and during the Norwegian campaign. Group Captain Pearce had made the first of many bomb attacks on the Scharnhorst while it was hiding in the
Norwegian fiords.

Before going on to a distinguished scientific career at Cambridge, Cockcroft had served as an artillery officer
in World War I. At the outbreak of war, he went back to the Army to advise on a wide range of Army research projects and on his return from America, he was due
to be appointed head of ADRDE at Christchurch. As the last and most junior member of the group, I was the radar man, with experience of both ground and airborne
radar.

The purpose of the Mission, subject to carefully vetted security procedures, was to hand over to the US Services,
all the recent British technical advances. These included virtually every British secret - jet engines, rockets, predictors, radar, etc. Nothing was excluded.
The remainder of this note will deal only with the radar exchanges. During the first few weeks of August 1940, the members of the Mission collected all the
documentation available on recent wartime developments - manuals, circuit diagrams, blue prints, films - anything which gave factual evidence of what was being
done in Great Britain and what was projected. These were deposited in a black deed box, of the kind found in solicitor's offices, which was kept under close
guard in the headquarters of the Department of Supply in Savoy House in London, where Cockcroft had an office. Easily the most important item in the box was a
sample of one of the first production magnetrons from the GEC Research Laboratory at Wembley. (This was the resonant magnetron invented by Boot and Randall at
Birmingham University in February 1940.) See editors note below. Up to that time only laboratory models had been made which worked off the pumps.
Megaw at Wembley then made the first production run of 12 sealed-off versions. They had a spectacular performance and delivered a pulse power of l0kW at a
wavelength of l0cm. This was a revolutionary development which gave promise of a whole new range of ground, shipboard and airborne radars, the performance of
which would be greatly superior to those already in existence.

At the end of August, Tizard went to the US by air to make preliminary arrangements. The rest of the Mission
followed by ship; they arrived in Halifax on 6th September and went on to Washington a few days later. Tizard had already established an office in the Shoreham
Hotel, near the British Embassy and made the initial arrangements with the US Navy and Army. It was planned to hand over the British secrets to an Army team
under the direction of General Mouborgne, the Chief Signals Officer and a Naval team under Admiral Harold Bowen, the Director of the Naval Research Laboratory.
Another vital contact made by Tizard was with the National Defense Research Council which had recently been formed under the Chairmanship of Dr. Vannevar Bush,
assisted by Karl Compton, the President of MIT and Dr.Conant, the president of Harvard.

The exchange of information with the US Army and Navy began on 12th September when a complete account of British
radar developments was given; it covered the whole field of ground based, shipboard and airborne radar. The US responded by giving actual demonstrations of
their equipment, at the Naval Research Laboratory in Anacostia and the Army Signals Research Establishment at Fort Monmouth NJ. It soon became clear that at
metre wavelengths, the US had technology which matched that of Great Britain. The great difference was that US systems existed only in ones and twos and they
had not seen much operational use. In Britain, by comparison, a sum of £l million sterling had been voted for the construction of a chain of air warning
stations to protect the Thames Estuary in December 1935. By 1938, a total of £10 million sterling had been allocated to the construction of 23 such air warning
stations along the East Coast and a further six stations along the South Coast. When the Tizard Mission arrived in Washington, this system had been fully
operational for over a year, and at that very moment was playing a decisive role in the Battle of Britain, from which England was already emerging as a certain
winner.

Editors note: the multi cavity resonant magnetron was invented in 1935 by Hollmann. See US patent no. 2,151,766
which was known to Randall and Boot when they built their magnetron in England in 1940.